The well-known Chechen regime-critical blogger was assaulted in his home in Gävle on 26 February.
With a hammer in full swing, the attacker attacked the blogger, who suffered a head injury but managed to defend himself.
In a bloody video, the blogger then made the attacker admit that he came from Moscow.
The man, a 29-year-old Russian citizen, has been arrested on probable cause on suspicion of attempted murder.
A woman has been arrested for aiding and abetting an assassination attempt.
Both deny any wrongdoing.
Ordered deed?
The preliminary investigation was moved on Monday from the police to the Security Police because it is considered to be under one of Säpo's areas of responsibility.
Which Säpo does not want to tell.
The blogger himself suspects that the government in the Russian sub-republic of Chechnya has ordered the act.
Former prosecutor Therese Stensson has answered in the affirmative to the question of whether an order from Russia is one of the clues.
After fleeing Chechnya in 2015, the blogger has made a name for himself on Youtube.
He wants to see an independent Chechnya but is not known for advocating violence.
He has been openly threatened by Chechen President Magomed Doudov since in a video calling the former Republican President Achmad Kadyrov, the father of current leader Ramzan Kadyrov, a traitor.
One in a row
The blogger is just the latest of at least twelve Chechen regime critics in exile in Europe who have been subjected to violence, several with fatalities.
Human rights organizations have identified Kadyrov as responsible.
As recently as January 30, a regime critic was killed with 135 stab wounds - in his hotel room in Lille, France.
And in August last year, a separatist was shot dead in a park in Berlin in broad daylight.
A man who has been revealed as an agent for the Russian security service FSB is in custody.